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The article presents a study of the association between the core gene irp2, fyuA deletion of the high pathogenicity island and avian pathogenic Escherichia coli (APEC). The study used the Red homologous recombination method to construct the irp2 gene deletion and irp2, fyuA genes deletion strains and real-time polymerase chain reaction (PCR) to evaluate their effects on the messenger RNA (mRNA) levels. It shows the importance of irp2, fyuA genes delection effect to the pathogenicity in APEC.

To detect avian beta-defensin 6 (AvBD6) quantitatively, a sandwich ELISA method was established and applied to detect the concentration of AvBD6 in serum. The results showed that the optimal dilution of capture antibody (mouse anti-B cell linear epitopes of AvBD6 polyclonal antibody), detecting antibody (rabbit anti-N-terminal of AvBD6 polyclonal antibody) and horseradish peroxidase (HRP)-conjugated goat anti-rabbit IgG was 2 500, 2 000 and 10 000, respectively. The standard curve regression equation was y =12 024x-2 583, ( R² =0.984 2) in the linear detection range from 20 to 320 ng/mL. The serum AvBD6 concentration of control group was slightly higher than that of ACTH group (P > 0. 05) after 1 day of ACTH (25 IU/kg BW) injection, but the AvBD6 concentration of the control group was slightly lower than that of ACTH group(P>0.05) after 5 d of ACTH injection; and the effect was not significant. The serum AvBD6 concentration of infected group after 24 h of Escherichia coli exposure or 3 h and 24 h of salmonella exposure were significantly higher than that of the control group (P<0.05). Our results indicated that AvBD6 involved in the resistance to system infection of Escherichia coli and salmonella. [ABSTRACT FROM AUTHOR]

The article presents a study which determines the residues of diclazuril and toltrazuril in chicken tissues by high performance liquid chromotography. Diclazuril and toltrazuril were extracted with acetonitrile from chicken liver, muscle and kidney. The method meet the demand in determination of residues of diclazuril and toltrazuril.

Two pairs of primers were designed to bind conserved genomic regions of goose parvovirus (GPV) and goose astrovirus (GAstV) to establish a simple, sensitive, and highly specific duplex quantitative PCR (qPCR) method to simultaneously detect the two viruses. The duplex qPCR can distinguish GPV (melting point: 82.1 °C) and GAstV (melting point: 79.8 °C) by the peaks of their individual melting curves. Mixed testing with other waterfowl viruses produced no nonspecific peaks. The established standard curves showed good linear relationships (R2 > 0.997) and the limits of detection (LOD) for GPV and GAstV were 5.74 × 101 and 6.58 × 101 copies/μL, respectively. Both intra- and inter-assay coefficients of variation were <2%, indicating that the method has good repeatability. Twenty tissue samples from diseased geese were examined with the duplex qPCR assay and conventional PCR. Duplex qPCR showed positive rates of 25% for GPV and 45% for GAstV, and the positive rate for GPV and GAstV coinfection was 15%, slightly higher than the results for conventional PCR. These results indicated that this duplex qPCR method is highly sensitive, specific, and reproducible, and is suitable for epidemiological studies to effectively control the transmission of GPV and GAstV. • We established a duplex SYBR green-based real-time qPCR assay to detect GPV and GAstV. • The melt curve temperature of GPV and GAstV was 82.1 °C and 79.8 °C. • This method has the advantages of high sensitivity, good specificity and reproducibility. [ABSTRACT FROM AUTHOR]